1. Field of the Invention
The present invention relates to a surgical apparatus for a vitreous, and more particularly, to the surgical apparatus which is utilized for removing tissue of a vitreous in an eyeball.
2. Description of Related Art
A vitreous cutter is a handpiece, which is utilized for operating upon a vitreous. The vitreous cutter sucks intraocular tissue through a suction hole, provided on an end of an outer tubular blade, thereby introducing the intraocular tissue therein. With its state, the vitreous cutter removes the tissue by moving an inner tubular blade (a resection blade). Moving methods for an inner tubular blade are the following: a rotary method which causes an inner tubular blade to revolve in one direction; an oscillation method which causes an inner tubular blade to turn clockwise or counterclockwise; a guillotine method which causes an inner tubular blade to reciprocate forwards and backwards (along an axial direction (longitudinal direction) of an outer tubular blade), and the like.
Further, driving methods for moving the inner tubular blade are the following: an electric method which produces an electric power with an electric motor or an electromagnet, provided in a handpiece, to cause an inner tubular blade to move; a pneumatics method which charges with and discharges a compressed-air (gas) intermittently to cause an inner tubular blade to move, and the like. Among these driving methods, at the present time, a pneumatics method is the main current because a handpiece can be lightened and it is disposable.
Herein, a conventional vitreous cutter of a pneumatics type will be described with referring to FIG. 4 (the description is made with respect to a guillotine method). A gas chamber 42 of a vitreous cutter 40 is charged with compressed-air (gas) from a compression pump 41 by a solenoid valve 46. Thereby, a pressure in the gas chamber 42 rises up, its applied pressure pushes and forces a holder 43 to move to a feed (forward) direction (a left direction in FIG. 4). As a result, the inner tubular blade 44 fixed to the holder 43 moves forwards along an outer tubular blade 45 and removes a vitreous body V which is being sucked through a suction hole 45a. After resection (removal), by making the gas chamber 42 communicate with the outside air (atmosphere) with the solenoid valve 46, the air contained in the gas chamber 42 is discharged into outside and the pressure falls down. A spring 47, therefore, forces the inner tubular blade 44 to turn back (backwards) (a right direction in FIG. 4). Reference numeral 48 denotes a muffler fixed to an exhaust hole of the solenoid valve 46 to reduce exhaust noise.
For the purpose of accurate resection of tissue, recently, the following has been required: to reduce an amount of resection during one stroke of the inner tubular blade, but to increase a number of reciprocating motion (a number of stroke) per unit time. Accordingly, it has been important that acceleration of a moving speed of the inner tubular blade.
In the case of a vitreous cutter, however, a return speed of a pneumatics type depends on a spring force, thus there is upper limit in acceleration. To make a spring robust enables an inner tubular blade to accelerate a return speed; but it needs a strong power in order to force the inner tubular blade forwards toward the suction hole. Disadvantageously, a large compression pump (compressor) should be used. Additionally, it is difficult to make an inside spring robust, for the purpose of accelerating an existing (conventional) vitreous cutter of a pneumatics type.
The present invention has been made in view of the above circumstances and has an object to overcome the above problems and to provide a surgical apparatus for a vitreous, which enables a resection cutter to speed up, and enables the operators to perform the accurate and efficient surgical operation, without making the apparatus large.
To achieve the object and in accordance with the purpose of the present invention, as embodied and broadly described herein, a surgical apparatus for removing a vitreous in an eyeball, comprises a cylinder, a piston disposed in the cylinder so as to be capable of moving, a moving device for reciprocating the piston in the cylinder, and a vitreous cutter. The vitreous cutter comprises a first gas chamber which connects with a second gas chamber in the cylinder via a tube, an outer tubular blade having a hole, an inner tubular blade, a moving body which is capable of moving in a longitudinal axial direction of the outer tubular blade with holding the inner tubular blade, and an energisation device which causes the moving body to perform a backward movement toward the opposite side of the hole relative to the outer tubular blade. The inner tubular blade and the moving body are caused to perform a forward movement toward the hole relative to the outer tubular blade by a pressure rise in the first gas chamber, the pressure rise being caused by the forward movement of the piston, and to perform the backward movement relative to the outer tubular blade, which is accelerated by a negative pressure by a pressure fall in the second gas chamber connected to the first gas chamber via the tube, the pressure fall being caused by the backward movement of the piston.
According to the present invention, a surgical apparatus for a vitreous enables a resection cutter to speed up without making an apparatus large, thus enabling the operators to perform a surgical operation accurately and efficiently. Further the aspect of the present invention may also be applied to the conventional vitreous cutter.